Testis & paratestis

Germ cell tumors

Teratoma-neuroendocrine tumor

Last author update: 1 September 2012
Last staff update: 17 July 2023 (update in progress)

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PubMed Search: carcinoid [title] well differentiated neuroendocrine tumor

Rafael E. Jimenez, M.D., M.H.A.
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Cite this page: Jimenez R. Teratoma-neuroendocrine tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testiscarcinoid.html. Accessed October 3rd, 2023.
Definition / general
  • Low grade neuroendocrine carcinoma, similar to counterpart at other sites
  • Usually monomorphic cells growing in solid nests, trabeculae or pseudoglands
  • Also called pure neuroendocrine carcinoma
  • Previous called carcinoid tumor, well differentiated neuroendocrine tumor
  • Rare ( < 1% of testicular neoplasms), mean age 46 years
  • Carcinoid tumors are neuroendocrine tumors derived from enterochromaffin (Kulchitsky) cells that secrete serotonin and most commonly arise in GI and respiratory tracts
  • In testis, presumed to be a monodermal teratoma, although 20% have other teratomatous elements
Clinical features
  • Only 10% have clinical carcinoid syndrome
Prognostic factors
  • Metastatic disease is associated with carcinoid syndrome, tumor size 7 cm or more (Cancer 1993;72:1726)
Case reports
  • Excision; occasionally metastasizes
Gross description
  • Solid, yellowish tan, well circumscribed
  • Cysts reflect other teratomatous elements
Gross images

AFIP images

Solid, tan cut surface

Microscopic (histologic) description
  • Islands of cells forming small acini; cords forming rosettes or sheets
  • Cells have granular eosinophilic cytoplasm, round nuclei with granular chromatin
  • Usually no intratubular germ cell neoplasia, no / minimal mitotic activity, usually minimal atypia or necrosis
Microscopic (histologic) images

AFIP images

Well defined acini and
solid islands of cells
separated by fibrous stroma

Eosinophilic cytoplasm and
round nuclei with coarsely
granular chromatin

Images hosted on other servers:

Insular pattern, chromogranin+

Intratubular germ cell neoplasia

Placental-like alkaline phosphatase

Testicular carcinoid tumor

Cytology description
  • Isolated or sheets of tumor cells with granular cytoplasm, round nuclei, uniformly distributed fine chromatin
Negative stains
Electron microscopy description
  • Neurosecretory granules
Molecular / cytogenetics description
Differential diagnosis
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